1. Field of the Invention
The invention relates to a lighting device and a method for making the same, more particularly to a lighting device including a lead frame with light emitting diodes packaged thereon.
2. Description of the Related Art
Referring to FIG. 1, a lighting module 1 of a conventional lighting device is shown to include a printed circuit board 12 (or a ceramic board) with conductive traces 121, and a plurality of light emitting diodes 10 (hereinafter referred as LEDs) soldered to and arranged on the printed circuit board 12 so as to be connected to each other in series and/or parallel through the conductive traces 121. For reference, such lighting module 1 is disclosed in, for example, U.S. Pat. Nos. 6,480,389B1, and 6,498,355B1.
The LEDs 10 of the conventional lighting module 1 can be formed using any well-known method. For example, the LEDs 10 can be formed by respectively attaching light emitting diode dies (not shown) to a plurality of die mounting parts of a lead frame or a stamped metal sheet (not shown), and packaging each of the light emitting diode dies using an encapsulant or lens (not shown). The packaged LEDs 10 are removed singly from the lead frame and then placed in an array on the printed circuit board 12 to proceed with a soldering step.
However, the soldering step requires a reflow soldering process, which is not only complicated but also can encounter an incidence of false soldering, generate high temperature heat that can damage the LEDs 10, and produce poor solder connections between the LEDs 10 and the printed circuit board 12. Besides, since the printed circuit board 12 is not heat conductive and is usually disposed between the LEDs 10 and a heat sink (not shown), it can interrupt heat conduction from the LEDs 10 to the heat sink, thereby reducing thermal dissipation and shortening the service life of the LEDs 10.